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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "btime_int.h"
static int same_addr(struct sockaddr_in *a, struct sockaddr_in *b);
/*
* btime --
*
* Return the boot time of a remote host if that host is running the
* btimed deamon.
*
* Returns:
* btime, or 0 on failure.
*/
unsigned int
btime(const char *host)
{
int sd;
char msg[BTIME_MSGLEN];
struct sockaddr_in serv_addr;
struct sockaddr_in my_addr;
struct sockaddr_in resp_addr;
int serv_addr_len;
int resp_addr_len;
struct hostent *hostent;
in_addr_t inaddr;
unsigned int btime;
ssize_t nbytes;
int retry;
if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
fprintf(stderr, "Could not create socket: %s\n",
strerror(errno));
return 0;
}
memset(&serv_addr, 0, sizeof serv_addr);
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(BTIME_PORT);
if ((inaddr = inet_addr(host)) != INADDR_NONE) {
memcpy(&serv_addr.sin_addr, &inaddr, sizeof inaddr);
} else {
if ((hostent = gethostbyname(host)) == NULL) {
return 0;
}
memcpy(&serv_addr.sin_addr, hostent->h_addr, hostent->h_length);
}
memset(&my_addr, 0, sizeof my_addr);
my_addr.sin_family = AF_INET;
my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
my_addr.sin_port = htons(0);
if (bind(sd, (struct sockaddr *)&my_addr, sizeof my_addr) < 0) {
fprintf(stderr, "Could not bind to local address: %s\n",
strerror(errno));
return 0;
}
memset(msg, 0, BTIME_MSGLEN);
for (retry = 0; retry < MAX_RETRY; retry++) {
serv_addr_len = sizeof serv_addr;
if ((nbytes = sendto(sd, &msg, BTIME_MSGLEN, MSG_DONTWAIT,
(struct sockaddr *)&serv_addr, serv_addr_len)) < 0) {
if (errno == EAGAIN) {
usleep(retry * 100);
} else {
/* Non EAGAIN error... */
break;
}
} else {
break;
}
}
memset(&resp_addr, 0, sizeof resp_addr);
memset(msg, 0, BTIME_MSGLEN);
for (retry = 0; retry < MAX_RETRY; retry++) {
resp_addr_len = sizeof resp_addr;
if ((nbytes = recvfrom(sd, &msg, BTIME_MSGLEN, MSG_DONTWAIT,
(struct sockaddr *)&resp_addr, &resp_addr_len)) < 0) {
if (errno == EAGAIN) {
usleep(retry * 100);
} else {
/* Non EAGAIN error... */
break;
}
} else if (!same_addr(&serv_addr, &resp_addr)) {
char *rstr = strdup(inet_ntoa(resp_addr.sin_addr));
char *sstr = strdup(inet_ntoa(serv_addr.sin_addr));
fprintf(stderr, "Got response from %s instead of %s\n",
rstr, sstr);
free(rstr);
free(sstr);
continue;
} else {
break;
}
}
if (nbytes == 0) {
btime = 0;
} else {
btime = strtoul(msg, (char **)NULL, 10);
}
close(sd);
return btime;
}
/* same_addr
*
* Compare to struct sockaddr_in's
*
* Returns:
* 1 if the addresses match
* 0 if the addresses are different
*/
static int
same_addr(struct sockaddr_in *a, struct sockaddr_in *b)
{
if (a->sin_family != b->sin_family) {
return 0;
} else if (a->sin_addr.s_addr != b->sin_addr.s_addr) {
return 0;
} else {
return 1;
}
}
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